The present invention relates to sensitometry and more particularly to apparatus for exposing sensitometric and bar code data onto photosensitive media in a manufacturing environment.
The use of a sequence of reference calibration patches exposed on a roll of film to enable better exposure control during optical printing is known in the art. See for example U.S. Pat. No. 5,767,983 issued Jun. 16, 1998 to Terashita. The use of reference calibration patches has also been shown to be useful in determining correction values for scanned film data used in digital printing. See for example U.S. Pat. No. 5,667,944 issued Sep. 16, 1997 to Reem et al. and U.S. Pat. No. 5,649,260 issued Jul. 15, 1997 to Wheeler et al.
U.S. Pat. No. 5,075,716 issued Dec. 24, 1991 to Jehan et al. shows apparatus for exposing reference calibration patches on photosensitive media that includes a light source, and a bundle of optical fibers for transporting light from the light source to the photosensitive medium. The exposures to the photosensitive medium are controlled by providing groups of fibers having different numbers of fibers in each group and by apparatus for adjusting the spacing between the fiber bundles and the exposure plane. Furthermore, the exposure is accomplished by contacting the surface of the photosensitive medium with the print head of the apparatus to precisely locate the exposure plane and minimize flare.
There are many problems experienced with the use of conventional sensitometric apparatus to apply reference calibration patches to film. One problem is that contact exposures are not desirable in the manufacturing environment, since the surface of the film can be damaged or contaminated by contact with the print head of the sensitometer. Another problem is in exposing film at 4log E levels using a non-contact exposure apparatus without causing excessive image flare. Another problem is in providing a high enough exposure to expose the reference calibration patches in a short enough time (e.g. less than 100 milliseconds) to be compatible with the dwell time available for printing during the manufacturing process. An example of film manufacturing apparatus is described in U.S. Pat. No. 5,461,450 issued Oct. 24, 1995 to Long, et al. The film is transported in the apparatus using an intermittent motion that constrains the dwell time (the time that the film is stationary and the perforator punches are engaged with the film) as described above. A further problem relates to the size of both the conventional sensitometric apparatus and the size of the exposures produced thereby. It would be desirable to locate the sensitometer for exposing reference calibration patches into the manufacturing equipment of the photosensitive materials, where space is at a premium, to provide the most accurate placement of the patches and maximize the manufacturing system performance. It is also desirable to locate the sensitometric exposure device along with a barcode exposure device for the purpose of printing associated metadata and controlling both devices with a central control system There is also a need for a sensitometer that is easy to set up, reliably maintains its calibration in the manufacturing environment, and can automatically setup to meet the exposure needs of various product types without interrupting the process flow. A further need is to provide a sensitometer that is capable of reliably providing millions of exposures without failure or adjustment.
There is a need therefore for an improved apparatus for exposing sensitometric and meta data onto photosensitive media that avoids the problems noted above.
The need is met according to the present invention by providing an apparatus for exposing reference calibration patches onto photosensitive medium, including: a light source; a plurality of optical fibers, one fiber for each element to be exposed; a light collector having an input port for receiving light emitted by the light source and an output port for delivering light to one end of the optical fibers; a plurality of light attenuators located with respect to the optical fiber for individually attenuating the light transmitted by each fiber; a projection print head located at the other end of the optical fibers for directing light from the fiber onto the photosensitive medium; and a controller connected to the light source for measuring and controlling the light output of the light collector.
According to a further aspect of the invention, the apparatus includes a data printer having: a second light source; a two dimensional liquid crystal light modulator for modulating the light from the second light source; optics for projecting an image of the light modulator onto the photosensitive medium; and the controller being connected to the light modulator and the light source for applying a two dimensional bar code image signal to the light modulator and activating the light source for exposing the two dimensional bar code onto the photosensitive medium.
The apparatus operates as a system that prints both barcode data and sensitometric information on the photosensitive medium transported under the print heads located on a web transport of a photosensitive medium manufacturing machine.
The apparatus of the present invention has the advantage of providing: a broad dynamic exposure range of up to 4 Log E; rapid exposure times regardless of film type; non-contact printing, whereby no part of the apparatus contacts the photosensitive and fragile film surface; precise, controllable, adjustable exposures; a reference calibration patch profile with a substantially flat profile shape at peak values along with a minimal flare skirt; and a precision of exposure of better than 1% over an 8xc3x97 range of film speeds and product sensitivities.
In the preferred embodiment, the apparatus is located on a perforation/printing station of a film manufacturing machine at a specific location where a predetermined frame stops, regardless of film length, thus allowing one fixed location printer system to generate various film lengths without need for operator intervention or setup for film length changes on the station. Physically printing the reference calibration patches and the barcode data in the same frame location (frame 0) during the same machine index dwell, allows for the most accurate placement of each printed image relative to the other, resulting in minimal dimensional variation between the two image geometries.
The printer control system allows for more efficient and reliable data transfer from the reference calibration patch printer to the bar code data printer. This allows the barcode data printer the capability of reporting on certain characteristics of the reference calibration patch printer and including that info in the data printed by the bar code printer.
Minimum space is required for implementation on a production manufacturing machine and a minimum impact on present spooler control system during printing, and can be configured for projection printing on a planar or radiused film surface. Its modular design provides for minimized setup and install time. The preferred XENON illumination sources provide long life, stable and high reliability compared to tungsten or other sources.
The use of optical fibers allows for the transport of precise signals through an electromagnetically noisy machine space. The small footprint, very fast cycle, and ease of maintenance, result in a significant improvement in overall performance compared to standard sensitometers. Separating light source from the print head and joining them with optical fibers allows for flexible placement of the print head on the machine, and easy replacement of the light source or print head.
Communications between the printer control system with the web transport control system allows for filmstrips with the same data message to be identified by cartridge ID and other specific data. The identification information can be stored in the factory. This identification can be used to provide data corrections or updates by communicating the updates to the photofinisher and using the identification information printed in the data and located on the cartridge to identify the affected filmstrips.